Maintaining a controlled environment is essential in many academic, industrial and medical settings, and controlling contamination entering that environment is very important. For example, many hospitals, factories, food preparation areas, spray-paint booths and laboratories utilise a controlled environment, which may be referred to as a cleanroom. Precautions are taken such as subjecting cleanroom staff to strict clothing regulations and using a gowning room where the staff can change clothes under “controlled” conditions so as to prevent any particulates from entering from the outside environment. Certain areas in a cleanroom may have more stringent measures than others, with packaging areas, corridors, gowning rooms and transfer hatches being incorporated to maintain strict contamination control measures.
In hospitals, cleanroom precautions can be used to try to reduce the incidence of infectious diseases spreading. In industry, particularly in the pharmaceutical, electronics, aerospace, catering, automotive, biomedical, IT, nuclear, optical and medical devices industries, it is often essential to ensure that products are free from contamination. Contamination of a controlled environment poses a threat to product processes, the consequences of which are lower product yields, raised costs and decreased profits.
Contaminants are particles that enter an environment where they may potentially have a negative effect. There are many types of contaminants and they can have a wide variety of effects on different environments. Contaminants can be bacteria or other organisms that are potentially harmful to their surroundings. More familiar contaminants can be things such as dust and dirt.
Contaminants can be carried on any surface entering a controlled environment, or in the air. Particles can be suspended in the air for hours where they undergo rapid proliferation, contaminating the surrounding environment. Once there is no movement and turbulence stops, airborne contaminants fall. If they fall onto an unprotected floor they may rise again and be redistributed into the air as a result of the vortices created by the movement of personnel and wheeled traffic.
Studies have shown that over 80% of contamination enters a controlled environment through entrances and exits, mostly at or near floor level. As a result of this, attempts have been made to reduce the contamination entering a controlled environment by using particular floor coverings.
It is known to use particular floor coverings in entry and exit areas to controlled environments to attract, collect and retain foot and wheel borne contaminants, thereby reducing the contamination entering the controlled environment.
One type of flooring, known as polymeric matting, is particularly effective in certain situations in controlling particulate contamination. It is semi-permanently installed and can be cleaned as required. Dycem's Protectamat flooring system is an example of this. The polymeric matting comprises a single layer of polymer, usually a specially blended polymer formulation comprising polyester plasticisers leading to a tack that can attract and bind contaminants. This is typically at least 7 mm thick, making it heavy to manoeuvre. As noted above, this is a semi-permanent or permanent solution, in that the polymeric matting is particularly long-lasting and can be used for 3-5 years before replacement. This works very well when long term contamination control is required and the operator has sufficient resources to invest in such a system. However, it is less suitable for a situation where contamination control flooring is needed for a short period or at a low cost, for example, a testing laboratory, where testing is going on for a few days or for a few weeks.
“Peel off” mats, also known as adhesive floor mats or tacky mats, are also used in contamination control situations particularly where the need for contamination control is short lived, or there is not enough resource to fund installation of permanent contamination control flooring. These mats comprise a laminate of thin (0.1 to 0.2 mm) synthetic material layers, typically thirty layers, which are stuck together by a pressure sensitive adhesive to form a mat which is several millimeters thick. The mat is then placed on a floor to capture contaminants, for example, from feet or the wheels of trolleys. In use, the upper layer of a mat is removed from the base on a regular basis, exposing a new clean layer.
These “peel off” mats have several disadvantages. Firstly, and most importantly, the peel off mats do not work very well in comparison to polymeric matting. The surface tack is not as good as polymeric matting and does not retain nearly as many contaminants. Second, adhesive can be removed from the uppermost layer to adjacent floor surfaces by feet and wheels which can itself attract contaminants, meaning that peel off mats can be counterproductive by actually encouraging contaminants into the controlled area. Third, when an upper layer is removed from the mat it creates a considerable volume of waste which is difficult to recycle. Fourth, when removing an upper layer, contaminate particles can be released which may be hazardous to a user who may breath them in.
It is an object of the invention to overcome, or at least to mitigate, the disadvantages of prior art products.